Dynamical density functional theory for the drying and stratification of binary colloidal dispersions

TL;DR

This paper presents a dynamical density functional theory model for drying binary colloidal films, capturing stratification phenomena like small-on-top layering influenced by evaporation rate and particle adsorption.

Contribution

It introduces a novel theoretical framework that predicts stratification structures in drying colloidal films, aligning with experimental and simulation results.

Findings

Model accurately predicts stratification patterns.

Evaporation rate influences film structure.

Adsorption affects particle distribution.

Abstract

We develop a dynamical density functional theory based model for the drying of colloidal films on planar surfaces. We consider mixtures of two different sizes of hard-sphere colloids. Depending on the solvent evaporation rate and the initial concentrations of the two species, we observe varying degrees of stratification in the final dried films. Our model predicts the various structures described in the literature previously from experiments and computer simulations, in particular the small-on-top stratified films. Our model also includes the influence of adsorption of particles to the interfaces.